Air cooler system having temperature and humidity controlling means



Jul 26, 1949.

W. A. SPOFFORD AIR COOLER SYSTEM HAVING TEMPERATURE AND HUMIDITY CONTROLLING MEANS Filed Oct. 25, 1947 rllll vtrol mechanism.

Patented July 1949 TURE MEANS HUMIDITY CONTROLLING Warren A. Spoflord, Glen Ridge, N. 1., minor to General Electric Company, acorporation of.

New York Application October 25, 1947, Serial-No. 782,080

6 Claims. (01. 624) This invention relates to air cooling systems employing refrigerating machines of the compression type and particularl to arrangements for controlling the operation of the refrigerant evaporators of such systems. i

In the operation of air cooling systems it is desirable to control both the temperature and humidity of the air in the space to be cooled,

operates continuously to vary the temperature or humidity gradually or by small increments without interruption of the operation of the cooling unit. This modulating action may be secured, for example, by variable throttling of the flow of liquid refrigerant supplied to the evaporator. When the throttling operation requires the addition'of working parts in the refrigerant control it may be objectionable for many applications and, accordingly, it is an object of the present invention to provide an air cooling system including a refrigerant evaporator and an improved arrangement for varying the efiective cooling, surface of the evaporator.

It is another object of this invention to provide an air cooling system including a refrigerating machine and an improved arrangement for controlling the effective surface of the refrigerant evaporator which shall be of simple and rugged construction and which shall not require additional moving parts in the refrigerant con- Further objects and advantages of this invention will become apparent as the following description proceeds, and the features of novelty which characterize this invention will be pointed outwith particularity in the claims annexed to and forming a part of thisspecification.

For a better understanding of this invention reference may'behad to the accompanying draw-- ing in which Fig. 1 represents diagrammatically an air cooling system embodying the invention;

(not shown). The evaporator ,Iis connected in a' closed refrigerant circuit including a compres- $611.3 driven by a suitable motor}; Ia condenser '5, and a liquid receiver 6. Hot compressed re-,

frigerant is delivered by the compressor to the condenser where it is cooled by the passage of suitable cooling fluid over the surface of the condenser and is liquefied, the liquid refrigerant collecting in the receiver 6. From the receiver 6 the liquid flows through a liquid line 1 to a thermostatic expansion valve 8 having a ther-- mal bulb or feeler element 9 secured to the suction line of the evaporator I indicated at H). The evaporator as illustrated, by way of example, comprises four individual coils H. Each of the coils is supplied with substantially the same quantity of liquid refrigerant from a distributor l2 associated with the thermostatic expansion valve 8, and the outlets of all coils are connected to the suction line H) acting as a manifold. The coils are thus in parallel to the refrigerant circuit and are also in parallel in the air circuit, each coil serving a separate zone of the air duct so that each coil treats a separate volume of air. During the operation of the system the thermostatic expansion valve 8 operates to maintain substantially constant the value of superheat of the vaporized refrigerant withdrawn through the suction line I0 as determined at thelocation of the control bulb 9. In order to change the effective surface of the evaporator l during the operation of the system, a damper I3 is provided in a position so that it may be moved across the face of the top coil ll to limit or restrict the passage of air over that coil. The damper I3 is biased to its open position bya spring l4 and is arranged to be closed by a solenoid winding l5 arranged to move an armature l6 to the right upon an increase in the current flowing through the winding. The energization of the winding 15 is controlled by a variable resistor l1 actuated by a device which is responsive to a condition of the air and has been illustrated as a coiled bimetallic element It responsive to the temperature of the air entering the evaporator. The coil I5 is connected to a source of electric current I 9. through the resistance l1 and the thermostatic element I8 is arranged to reduce the amount of resistance-in the circuit by rotating a contact 20 in a counterclockwise direction upon a decrease in the temperature of the air. Thus the damper I 3 is moved gradually into the path of the air flowing over the top coil ll as the contact .20 is moved gradually in a counterclock wise direction. As the flow of air over the top coil II is restricted, less refrigerant is evaporated in the coil and liquid refrigerant flows from the coil into the suction line Hi. This liquid refrigerant lowers the resultant temperature at the location of the temperature bulb 9, and the valve v of the condition 8 closes to reduce the amount of refrigerant supplied to the four coils If so that the superheat of the gas is restored to the required value.

of the entire evaporator is reduced accordingly.

The average temperature of the air leaving the evaporator is thereby raised and overcooling is avoided. It will readily be understood that the operation of the thermostatic control 18 will tend to maintain substantially constant the average temperature of the air passing over the evaporator. The arrangement .of the damper I; thus makes it possible to control the eflective surface of the evaporator I without providing additional moving parts within therefrigerant circuit and provides a simple and easily constructed device for securing a modulated control of the air passing through the duct. I 1

In addition to controlling the effective surface of'the evaporator in accordance with the temperature of the air to be cooled it may also be desirable to limit the loading of the system to prevent overloading of the motor during temperature conditions of the fluid employed to cool the.

condenser. In Fig. 1 there is provided an additional damper 2| which is arranged to vary the proportion of air flowing over the lowermost coil The operation of the damper 2| in'changing the capacity of the system is the same as that of the damper l3, so that upon restriction of the: air flowing over the lowermost coil of the evaporator the load carried by the evaporator isreduced and overloading of the motor is prevented.

In some cases it may be desirable to combine the control functions for air temperature regulation and motor overload prevention in a single mechanism. The air cooling system of Fig. 2 is essentially the same as that of Fig. 1 and corresponding parts have been designated by the same numerals. In this figure a single damper 26, which may be of somewhat greater area than the damper l3 of Fig. 1, is provided in a position to be t moved over the face of the uppermost coil I l and also in its closed position to partially restrict the circulation over the next coil I l. The damper 2B is actuated by an arm 21 which is biased by a spring 28 to the'damper opening position. The operation of the damper in response to the control 18 is the same as that of the damper I3 in Fig. 1 and controls the air temperature in the same way. The load carried by the motor 4 is limited by operation' of a control bellows 29 which moves against the arm 21 when the temperature of the motor 24 rises above a predetermined value. the

temperature being determined by a thermal bulb or feeler element 30 arranged in the motor windings' to be responsive to the motor temperature. Thus the motor temperature control will take over and move the damper toward its closed position, if required, regardless of the position determinedvby the operation of the control I8. The functions performed by both dampers i3 and 2| of Fig. l are thus performed by the single damper:- 26 of Fig. 2 'and,'as already mentioned, this damp- V er may be made of somewhat greater area than the dampers II and H in order to close ofl a part of a second coil should the motor overload control require further restriction after the temperature control has moved the damper to its extreme position in response to the control 18. It will readily be understood that motor temperature or condenser pressure may be employed interchangeablyv to determine the; load condition on the motor.

While the invention has been illustrated in connection with specific forms of apparatus, other modifications will readily occur to those skilled in the art. rangement ofthe coils ll may be varied to suit particular applications, and although the control H has been illustrated as arranged in the air stream entering the evaporator other locations may be employed in accordance with well-known practice in the art and the control may be made to respond to humidity instead'of temperature if desired.

What I claim as new anddesire to secure by tor for maintaining a predetermined amount of superheat in the vapor withdrawn from said evaporator, a distributor for directing substan tialiy equal quantities of refrigerant to each of said conduits, and means arranged to change the relative proportion of air flowing over one of said conduits for varying the effective surface of others of said conduits.

2. An air cooling system comprising a duct arranged for thecirculation of air therethrough, a refrigerant evaporator arranged in said duct for cooling the air passing therethrough, said evaporator comprising a plurality of refrigerant conduits each arranged ina separate zone of said duct, said zones being arranged in parallel in relation to the direction of air flow, means for sup plying liquid refrigerant to said evaporator and for withdrawing vaporized refrigerant therefrom, a thermostatic expansion valve arranged to control the admission of refrigerant to said'evaporator for maintaining a predetermined amount of superheat in the vapor withdrawn from said evaporator, a distributor for directing substantially equal quantities of refrigerant to each of said conduits, andvmeans including a damper arranged to be moved into the path of air ilowing over one of said conduits for changing the proportion of air flowing over said one conduit to vary the effective surfaces of the others of said;

For example, the number and aration to the direction of air flow, means for evaporator for maintaining a predetermined ply n l q refrigerant to S evaporator amount of superheat in the vapor withdrawn 1 for withdrawing vaporiz r frig r n therefrom said evaporator, a distributor for directing m. a h rm ief xp ion valv arranged substantially equal quantities of refrigerant to control the admission of refrigerant to said 5 h" of d ond it a damper arranged i ipe for maintaining a predetermined said duct for limiting the circulation of air :ount of sup rh i the v po withdrawn from through one of said zones, means for biasing said d evaporator, a distributor for directing subdamper to its open position, and means responnti liy equal quan iti s of refri r t o each sive to the temperature of air circulated through said conduits, and means responsive to a con- 0 said duct for actuating said damper to change ion of the air circulated over said evaporator the proportion of air flowing through said one chan in h tiv p p n of air W- zone to vary the effective surfaces of the conduits :over one of said conduits for varying the efleci th th of id zones,

e surfaces of the others of said conduits. 6. An air cooling system comprising a duct i. An air cooling system comprising a duct arranged for the circulation of air therethrough, f r for he circula ion of air there h o a refrigerant evaporator arranged in said duct r fri nt ev p r rr nged in said duct for cooling the air passing therethrough, said c o n the ir P in r hr h, a evaporator comprising a plurality of refrigerant p or p in a urali y f refrig r n conduits each arranged in a separate zone of said adults each rr n ed in a sep r e zone of duct, said zones being arranged in parallel in a duet, d zones be a an ed in pa a el relation to the direction of air flow, means includrelation to the direction of air flow, means ing a f i nt condensing unit for supplying 7 111 9 34 18 liq fri t to said evaporator liquid refrigerant to said evaporator and for d for withdrawing vap d refrigerant therewithdrawing vaporized refrigerant therefrom, a m, a thermostatic expansion valve arranged thermostatic expansion valve arranged to control control the admission of refrigerant to said the admission of refrigerant to said evaporator ap rator for ma nta in a p d t rmi d for maintaining a predetermined amount of wa of ip in he vapor withdrawn superheat in the vapor withdrawn from said im said evaporator, means including a refrigevaporator, a distributor for directing substanrnt distributor connected between said evapoo tially equal quantities of refrigerant to each of tor and said valve for connecting said consaid conduits, means responsive to a condition of i in p r l and for pply i lly the air circulated over said evaporator for changual quantities of refrigerant to each of said ing the relative proportion of air flowing over nduits, and means including a damper arranged one of said conduits for varying the effective surbe moved into the P Of 'flowing over one 5 faces of the others of said conduits, and means said conduits for changing the proportion of responsive to the loading of said condensing unit r flow ov r said o du t to y the for modifying the operation of said last men- 'ective surfaces of the others of said conduits. tioned means to prevent overloading of said unit. 5. An air cooling system comprising a duct WARREN A. 'SPOFFORD. ranged for the circulation of air therethrough, 4o

refrigerant evaporator arranged in said duct REFERENCES CITED r cooling the air passing therethrough, said aporator comprising a plurality of refrigerant nduits each arranged in a separate zone of said 7 The following references are of record in the file of this patent:

ict, said zones being arranged in parallel in 45 UNITED STATES PATENTS iation to the direction of air flow, means for Number Name pplying liquid refrigerant to said evaporator 1957 292 Reves gn id for withdrawing vaporized refrigerant there- 2o91563 Palmer Mm 1937 cm, a thermostatic expansion valve arranged 2:182:66 Gowans Dec.

control the admission of refrigerant to said so 2,236,190 Wolfe Man 19 

